The StormBlaster™  is  a powerful fluid-driven rotary jet tank cleaner. Based on technology for cleaning oil tankers, it is extremely robust and can be deployed in cold, dirty and corrosive environments with little or no maintenance requirements, making it  ideal for cleaning large stormwater attenuation tanks. It is a modular system that can be fitted to any size or shape of tanks.

Running StormBlasters in sequence v all at once

For stormwater tanks, multiple StormBlasters often need to be installed, each responsible for cleaning one part of the tank. With large tanks that have multiple StormBlasters installed, it is possible to have the units running all at the same time. Having multiple units running simultaneously means that the overall flow rate required from the supply pump increases accordingly. As a result, customers will often want to run StormBlasters one at a time in sequence to clean the tank in stages. This is a common practice that helps reduce the required pump duty and the supply pipe sizes. If this is done, however, thought needs to be given to how the sequencing of the multi-stage clean is performed.

Simple manual v electronically actuated valves

Simple manually turned valves are very cheap and in tanks with a single StormBlaster™ unit, this is often how the system is controlled. When the cleaning system needs to be turned on, the pump is started and the valve is opened manually. When the cleaning cycle is complete after a set time, the valve is switched off. Naturally, that means that there needs to be someone on site to manually activate the valve at the required time.

If multiple StormBlasters are to be run in sequence, then obviously a series of valves need to be shut on and off manually. This will require the operator to set timers and remember when and in which order to close and open the valves so that each StormBlaster™ is shut on and off correctly. With the correct operator training and written processes, it is a viable, low-cost control sequencing system. But as the number of stages in the clean increase, the sequencing becomes more complex.

Typically, a StormBlaster™ will take about half an hour or so to run through its cleaning cycle so a two-stage clean will mean someone has to turn on and off the valves at the half-way mark. The process will thus need someone's attention for about an hour. But if we have a very large tank with, say, eight units installed, we’d have a four hour process with eight valve changes to manage which becomes more and more difficult for operators to do.

The alternative to manual valves is to have electronically actuated valves that are controlled remotely. This can be completely automated so the valves are timed to come on and off as the system runs through its multi-stage cleaning cycle. This type of system could even be connected to a level sensor that automatically starts the cleaning cycle as soon as the tank is emptied.

Multiple units, one valve

With both manual or automated valve sequencing, it's possible to group the StormBlasters into pairs, triplets, or quads controlled by a single valve. This will simplify the pipework and reduce the number of valves and it will also make the control system simpler. For example, a tank with eight installed units could have the whole sequence run in eight separate stages - four pairs of two or two pairs of four. In this way, a complex eight-stage cleaning could be reduced to a simple two-stage cleaning.

Making the right choice

The beauty of the StormBlaster™ system is its flexibility and versatility. From a cleaning perspective, it doesn't matter too much how the system is sequenced and controlled. If each unit gets enough time to complete its cleaning cycle and the correct flow rate of wash water is supplied, then the whole tank will be cleaned properly. However, the choice of how to control the system and how to split up multi-stage cleans can have a significant impact on the overall cost of the whole system.

So, here's some general rules. The more stages the clean is divided into, the lower the overall pump and pipework cost will be. The more sequences required, the greater the need for automated control valves and the costs associated with those. Manually activated valves can greatly reduce control systems cost, but increase the need for operator attention. Running StormBlasters in pairs, triplets or quads will reduce the number of stages required and hence reduce the complexity of the control system, but will increase the size of the supplied pipework and the pump accordingly. The more remote and sparsely manned the site, the less viable manually actuated systems are.

When designing multi-stage cleaning systems for large storm tanks, all the factors above should be considered to get the most cost-effective overall solution. Even though we will often not be involved in the supply of the wash water fluid delivery and control systems, we're happy to discuss this at the design phase of the project. With a bit of planning, a StormBlaster™ system will not only be the most effective way to clean a large storm tank, but also the most cost effective. A true win-win.